Superabsorbent water-resistant coatings for fiber-reinforced articles

ABSTRACT

A coating composition for forming a water-resistant coating on fiber-reinforced articles such as rods or cables. The composition comprises an aqueous solution of a superabsorbent water-soluble polymer, a viscosity modifying agent, and optionally a lubricant. The coating formed by applying the composition effectively prevents the treated surface from water-permeation damage by absorbing water that contacts the layer containing the superabsorbent component.

TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION

The present invention relates to a high strength superabsorbent coatingcapable of rapidly absorbing water, which is suitable for coatingreinforcing fibers, or for coating articles comprising reinforcingfibers, such as reinforced rods and cables. More specifically, thecoating is formed from a composition comprising a superabsorbent polymerprecursor which, upon cure, forms a polymer with a high water swellingability; and a film-forming polymer. As a modification to adapt thecoating to pultruded articles, the coating composition may also includea viscosity-modifying agent.

The inventive concept also relates to articles coated with thesuperabsorbent coating composition, such as glass rods; and methods ofapplying such coatings. The novel coating of this invention demonstratesa high level of water absorption in fresh and salt-water environments,and excellent spreading and coating ability when applied to a substrate.

BACKGROUND OF THE INVENTION

Deterioration caused by the invasion of moisture beneath the exposedsurfaces of articles used in outdoor environments is a well-knownproblem. This deterioration includes oxidative deterioration caused byreaction of water with the surfaces of reinforcing fibers used in thesearticles, as well as water-induced corrosion. In marine environments,the problems associated with waterlogging are particularly compounded bythe salinity of the environment. The presence of salt in such aqueousenvironments hastens the oxidative decomposition.

Articles affected by the deterioration described above includereinforced fibers made of glass, carbon, polymer or mixtures thereof, oritems containing such reinforcing fibers. The term “articles”, as usedherein, is specifically intended to include reinforcing fiber materialsknown in the art, as well as products made using one or more of thesefibers collectively or dispersed within a matrix of any type. The termalso includes articles manufactured using reinforced fiber products,such as structural materials or in equipment. Examples of such articlesinclude such as reinforced rods and cables, such as fiber optic ortelecommunications cables. These telecommunications cables are oftenused in situations where they are buried underground or submerged inwater over long periods. As such, protection from water damage iscritical to the structural integrity of these cables and to the successof the functions they are intended to perform. A telecommunicationscable, for example, may include a core comprising a glass rod that actsas a stiffening or reinforcing member. This rod contributes to therigidity of the cable. When water penetrates to contact the core elementof the cable, corrosion or chemical deterioration of the cableinfrastructure may result.

In order to combat the problems associated with this waterloggingdamage, several strategies have been devised in an attempt to providewater resistance to cables and other reinforced articles, and to protecttheir sensitive inner surfaces from contact with water or water vaporpresent in the surrounding environment. These techniques for makingwater-repellent articles have included wrapping the articles in aprotective sheathing material; or sealing the surface to be protected.Sealing techniques may include chemically manipulating the surface layerof the article to render it resistant to water-absorption, or applying arepellent coating.

The technique of covering the surface with a protective sheathingmaterial is conventional. It includes for example, using a wrap or tapemade of an impervious polymer with water-blocking ability, or treatingthe wrapping material with an emulsion or solution of a water-blockingpolymer. The sheathing process does not require application of achemical compound or treatment to the surface of the article, rather theprotection is derived only from the coverage by the sheathing material.

Coatings used to repel water traditionally have been composed ofsubstances that are both insoluble and impenetrable to water, andtherefore presented a physical barrier to encroaching moisture. Suchbarrier coatings have included materials such as greases or gels. In thecase of cables, for example, these coatings are applied by extrusionunder pressure. There are however, certain drawbacks associated withthis type of coating. Greases or gels are difficult to handle because oftheir slipperiness, and they contribute an unpleasant feel to the coatedarticle. This is an important factor to be considered in themanufacturing process, particularly because it affects the ease ofhandling of the cable during splicing operations. Greases and gels alsoundergo changes in viscosity at low or high temperatures. Theseviscosity changes may affect the freeze/thaw performance and thereforethe stability of the coating. Poor performance in these respectstherefore affects the stable performance of the cables.

More recently, greaseless, water-resistant dry coatings have beendevised which, of themselves, have some degree of water-absorbingcapacity. This ability to absorb water allows the coating to absorb themoisture contacting the article, while preventing direct contact withthe sensitive surfaces. The absorbent component in these drywaterblocking coatings is a dry, granulated superabsorbent polymer thatswells and absorbs upon contact with water. The superabsorbent polymersare usually characterized in terms of their swell rate, swell capacityand gel strength. Traditional uses for these dry superabsorbent polymershave primarily included personal hygiene product articles, foodpackaging articles and chemical spill cleanup compositions, howeverrecent experimentation has included using these dry polymers to formcoatings for other articles such as reinforced cables. For example, U.S.Pat. No. 5,689,601 to Hager, herein incorporated by reference, disclosesa dry waterblocking coating for reinforcing fiber articles using apowdered or granulated water-soluble dry blocking ingredient encased inone or more thin layers of a sheathing polymer. This casing restrictsthe degree of water absorption that can be achieved by the granularpolymer, and accordingly the swell capacity of this coating is limited.

The superabsorbent polymers traditionally used in dry waterblockingcable coating applications are dry, granular polymers that areincorporated into various substrates such as yarn, binders and tape. Thesubstrates typically also contain glass fibers as a form ofreinforcement. However, as discussed above, the coatings formed with drygranulated blocking agents suffer the limitations of limited waterswelling ability and swell rate as a necessary consequence of optimizingthe gel strength. In the context of surface coatings, gel strength isdefined as the ability to prevent water from wicking down the cableaxis, particularly when the cables are used in aqueous environmentswhere they are exposed to elevated water pressures. The swelling abilityis directly related to the degree of cross-linking of the superabsorbentpolymer. As the degree of cross-linking increases, so does the gelstrength, but there is a related decrease in the swell rate and swellcapacity of the polymer. The swell rate defines the amount of water thatthe coating absorbs over a fixed period of time. The swell capacitydenotes the maximum amount of water or fluid absorbed by the coating,based on a measure of its dry weight. Consequently, coatings made ofdry, granular, water-insoluble polymer are limited in theirwater-absorbing performance, as measured in terms of the swell rate andswell capacity.

Generally, coatings for reinforced fibers, strands and articles such ascables that are made from these fibrous materials are applied to thesurface of the fibrous material and then cured before furtherprocessing, if any, occurs. The means of applying coatings, in general,differs depending on whether a fluid coating is used or whether a solidparticulate coating is being applied.

In the case of powdered coatings, the coating process using granulatedwater-blocking agents involves several time-consuming and labor- andequipment-intensive steps that are directly related to the use of agranulated polymer. These steps include the need for one or moretreatments with a binding resin, and one or more applications ofpowdered resin at the powder-coating stations using apparatus such as afluidized bed.

The means for applying fluid coatings may include flooding, or dippingthe fibers or cables, for example in a resin bath and then removingexcess resin and form a consistent layer on the treated surface. In thecase of strands, rovings or cables, the product is in the form of acontinuous filament and therefore it can be passed through a stripperdie to remove the excess resin. Alternatively, the coating may besprayed onto the surface of the article. In order to form a coatinglayer that is thick enough to provide good coverage and protection fromwater penetration, the coating composition must be thick enough that itcan adequately coat the article in one pass through the coatingapparatus. In addition to thickness however, the composition must alsohave sufficient flowing ability to allow ready formation of a uniformcoating on the surface of the article, and to prevent clogging of thecoating apparatus, dye orifices or other machinery used to makepolymer-coated fibrous articles. Traditionally in the art, in order tomodify the viscosity of the fluid coating composition, dry particulateingredients such as a flocculent polymer or starch have been used. Thedifficulty with such compositions is that the resulting compositionafter this solid ingredient is added is not homogenous. Rather, thecomposition contains varying levels of a particulate material, whichmakes handling difficult and also compromises the spreadability of thecomposition.

There exists in the art then, a need for a waterblocking coatingcomposition which possesses excellent gel strength and wicking ability,as well as a high degree of water absorption and a concurrent, rapidswell rate. At the same time, a further need exists in the art for acoating composition that does not contain powdered polymer, and which,as a result, would not require a costly and labor intensive applicationprocess. At the same time it is desired that such a coating compositionexhibit good spreading and surface performance characteristics.

SUMMARY OF THE INVENTION

It has now surprisingly been discovered that highly absorbentwaterblocking coatings having an excellent water swelling capacity and arapid swell rate can be formed by incorporating a solution of asuperabsorbent polymer precursor into an aqueous solution used to coatglass fiber reinforced articles such as cables or rods. The polymerprecursor, when cured, forms a superabsorbent polymer. The novelcoatings containing this superabsorbent polymer are capable ofsubstantially instantaneous water absorption when exposed to aqueousenvironments.

Depending on the intended application, the absorbent coating may beenhanced by adding a viscosity-modifying agent. For example, where thecoating composition is applied to rods comprising glass, carbon, polymeror mixtures thereof, including a viscosifier imparts excellent spreadingability to the formulation. This viscosity-modifying agent is not aninsoluble powdered component, rather it is a polymeric solution ordispersion that can be easily incorporated into the coating composition.Hence, unlike waterblocking coatings previously known in the art, thecoating composition of this invention is in the form of a true solutionhaving substantially no particulate components.

In one aspect, this invention also relates to a process of forming acoating onto fibers or strands of a reinforcing material. The process ofcoating may further be applied to products containing reinforced fibermaterials, such as rods or cables formed from a composite making processsuch as pultrusion or injection molding. Generally, this processincludes the steps of applying the coating composition to the surface ofthe fibers, strands or articles, passing it through a stripper die toremove excess coating, followed by a drying or curing step.

The inventive concept further relates to articles containing reinforcingfibers made of glass, polymer, carbon or natural fibers that are madeusing the water-absorbent coatings of the present invention. Sucharticles include reinforcing fibers, strands, rods, rovings etc., eitherin continuous form or as chopped fibers, strands, or pellets; fabricscomprised of glass, polymer or natural fibers; and pultruded articlessuch as rods or cables. The pultruded articles may be comprised ofglass, carbon, one or more polymers, and mixtures thereof. Also, thecoating can be applied to corrugated metallic tubes and tapes used forrodent protection in fiber optic cables.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The composition of this invention is suitable for forming asuperabsorbent coating on the surface of fiber reinforcements andfibrous products or articles made using these reinforcements. Theproducts to which the composition may be applied can be divided into thebroad categories of fiber reinforcements, such as continuous strands, orcomposited articles comprising fiber reinforcements and one or moreother components. The ingredients included in the superabsorbent coatingformulation depend on the type of product to which the composition willbe applied.

As one embodiment, examples of fibrous reinforcement products in thefirst category mentioned above include strands or rovings made fromfiber-forming materials such as glass, carbon, polymers or mixturesthereof. The coating formulation for these products will preferablyinclude a small amount of a lubricant.

In another embodiment, the composited articles in the second categoryinclude articles that comprise a reinforcing fiber material as at leastone component thereof. Examples include articles formed in a pultrusionoperation. For example, the coatings of this invention can besuccessfully. applied to a pultruded rod or cable comprised at leastpartially of reinforcing glass fiber/polymer composite. The polymersthat may be used to form these pultruded articles include thermosettingresins, such as epoxies, polyesters and vinyl esters. The polymercomponent of the pultruded article may also be a thermoplastic resinthat has been heat-treated, however a thermosetting resin is preferred.As an example, a thermosetting epoxy resin such as a vinyl ester may becombined with glass strands in a pultrusion operation to form a rod thatcan be used as the stiffening member in a telecommunications cable.

The water resistant properties of the coatings of the present inventionare obtained by combining a solution of a non-toxic, environmentallysafe superabsorbent polymer precursor with the binder resin used to coatthe substrate articles. The superabsorbent polymer formed by thisprecursor possesses a surprisingly high capacity for absorbing water,and at the same time maintains a high gel strength in the cured coatingas a result of increased cross-linking. As mentioned previously, thispolymer uniquely provides water resistance by absorbing large quantitiesof water. As water contacts the coated surface of the article to beprotected, the coating absorbs water and swells in volume. By absorbingthe water, the coating effectively wicks away the moisture and thusprevents it from contacting the inner surfaces of the protected article.As a result, the sensitive inner surfaces remain dry and are protectedfrom watedogging deterioration. The coatings of this invention uniquelyachieve water resistance protection by absorbing water to preventmoisture penetration beneath the coating layer. This function isdistinctly different from the type of protection accomplished by thebarrier coatings more commonly known in the art, which protect thesubstrate by forming an impermeable barrier.

The non-toxic, environmentally safe superabsorbent polymer precursorused in the coatings of this invention may be selected from any suchpolymer capable of forming an aqueous solution for use in the coatingmixture, and which, upon cure, has a swell capacity and swell rate thatenables rapid absorption of large amounts of water followed bydesorption without loss of the polymer itself when the coating is dried.A polymer precursor suitable for use in the present coating willdemonstrate a swell capacity of up to about 400 times its initial dryweight when the coating is applied to reinforcing fibers or strands andcured.

The superabsorbent polymer precursor for use in the present inventionmay, for example, be selected from the group of water-solublepolyacrylates possessing the required ability to absorb and desorb largequantities of water, as has been previously mentioned. Thesuperabsorbent polymer precursor is preferably used in its anionic formas a salt of a corresponding alkali or alkali metal salt. The polymersalt is in the form of an aqueous solution that is either clear orslightly cloudy in appearance. A desirable solids content is in therange of from 30-35% weight. The solution also has a specific gravity ofabout 1.1 grams per milliliter and a viscosity of about 1000 mPas atabout 20° C. The solution is typically slightly anionic, having a pH offrom about 6 to about 8. One example of an acceptable superabsorbentpolymer precursor is a water-soluble anionic polyacrylate in aqueoussolution.

If the coating is to be applied to pultruded articles, aviscosity-modifying agent may also be added to the coating composition.The role of this viscosifier is to create a spreading consistency thatwill enable adequate coating of the pultruded article after it has beenpassed through a stripper die. The viscosifier also provides goodflowing ability and prevents clogging of the coating apparatus and dieorifices. Viscosity modifying agents capable of forming a true solution,such as alkyl cellulose or acrylamide polymers, may be used in thecoatings of this invention. A preferred viscosifier for use in thepresent coatings is a polyacrylamide in aqueous solution. Thepolyacrylamide solution is particularly suitable because of itscompatibility with the superabsorbent polymer precursor solution and thefilm-forming binder component.

The binder component used in the coating compositions of this inventioncan include any polymeric material customarily used as a binder incoating compositions for reinforced fiber-containing products. Thebinder preferably comprises a film-forming polymer or polymer latex thatis a thermosetting resin or a thermosetting resin with somethermoplastic properties to enhance the flexibility of the coating. Thefilm-forming binder is also necessarily compatible with thewater-absorbing polymer and with the viscosity-modifying agent, in thatit promotes combination of the ingredients in the coating composition,and also facilitates adherence of the coating to the surface once it isapplied. The film-former further provides a tough film with preferablyno surface tackiness or flaking of the coating after it is cured. Thefilm-forming polymer comprised in the binder may for example be apolyester, urethane, epoxy, latex or mixtures thereof. The latex may inturn be selected from an acrylic latex, a styrene-butadiene latex, ormixtures thereof. Preferably, the binder is a film-forming urethane thatpromotes adherence of the water-absorbing polymer to the treated surfaceafter it is dried. An example of a desirable film-forming binder isWitcobond W320, which is a polyurethane film-former available from WitcoChemical Co.

Optionally, the coating composition may also include one or moreadditives selected from the group consisting of lubricants and wettingagents. Lubricants are added to enhance the handling of thepolymer-impregnated strand in subsequent processing. Where the coatingis applied to fiber reinforcements such as glass strands, a lubricant ispreferably added to improve adherence of the coating to the strand.

The wetting agent is added to facilitate contact between the dispersionand the fiber surface. Any conventional wetting agent that is compatiblewith the other ingredients of the sizing composition can be used.

When the coatings of the invention are applied to the surfaces ofreinforcing fiber strands and cured, they demonstrate a swell capacityof from about up to about 400 times the initial dry weight of thewater-swellable polymer. Preferably, the swell capacity for this type ofapplication is from about 200 to about 400 times the initial dry weightof the water-swellable polymer. Where the coatings are applied and curedon the surface of articles such as rods or cables, the swell capacityranges up to 120 times the initial dry weight of the water-swellablepolymer. In this context, preferably the swell capacity is from about 50to about 100 times the initial dry weight of the water-swellablepolymer.

The swell rate of the coating should also be high. The coatings of thisinvention demonstrate an exceptionally high swell rate, in the order offrom about 300% to about 2000% weight in the first minute, based on thetotal weight of the polymer and the fiber substrate. The rate of wateruptake varies depending on the salinity of the aqueous environment inwhich the coating is used. In fresh water, the swell rate is higher thancan be achieved in a saline solution such as a marine environment.However, whether the coating is used in either a fresh or salt-waterenvironment, its performance, as measured by the swell rate, isdemonstrably higher than has been previously achieved by drywaterblocking coatings known in the art.

In the method of making the coating compositions of this invention, theingredients are combined in liquid form to prepare the coating solution.A solution of the superabsorbent polymer precursor is first stirred toensure homogeneity, then added to a mixing tank. Deionized water is thenadded to the tank, and the lubricant, if desired, is then introduced.Next, the polyurethane in the form of an aqueous emulsion is pumped intothe tank. The viscosity-modifying agent is first premixed to form a 1%aqueous solution, and a sufficient amount of this aqueous solution isadded to the mixing tank. As a final step, the mixture is then stirred,without heating, and the resulting composition is ready for application.

The composition is contacted with the surface of the articles to becoated by a means suitable for applying a liquid coating. For example,the coating composition can be applied by passing reinforcing fiberstrands through a resin bath. Alternatively, the composition is appliedto an article to be coated by spraying, flooding, or by any other meanswhich permits the liquid coating to be contacted with the entire surfaceof the article. A further processing means may then be used to ensure aneven and adequate distribution of the coating layer. For example, fiberstrands or rods are coated with the coating composition are passedthrough a stripper die.

The coated articles are then dried and cured. The article coated withthe superabsorbent polymer precursor is heated to 212° F. for a periodsufficient to volatilize a substantial portion of the water. The polymerprecursor-coated article is then heated to approximately 280° F. to curethe polymer by cross-linking. Typically, polymers heated to aboveapproximately 300° F. lose the desired superabsorbent quality. Thedrying/curing step may be performed in an in-line oven. In a 25 footlong oven set to approximately 600° F. the polymer is cured at 380-490feet per minute, and preferably at 440-465 feet per minute.

Glass fiber reinforced articles having the water resistant coatingherein described may be used in applications where exposure to water orwater vapor is likely, and where the formation of a durable, resilient,flexible coating with good waterproofing properties is desired. Thefollowing examples are representative, but are in no way limiting as tothe scope of this invention.

EXAMPLES

Exemplary coating formulations were prepared by combining a film-formingbinder polymer, a water-absorbing polymer precursor solution and apolyacrylamide solution. The coating compositions were then applied topultruded glass-vinyl ester rods using a flooding process. After thecoating composition was applied, the rod was passed through a stripperof desired orifice size to control the amount of coating compositiondeposited on the surface of the rod. The rod was then heated tovolatilize the water component, then further heated to about 270° F. tocure the coating and activate the superabsorbent polymer precursor.

Example 1

In this example, a coating composition for treating pultrudedglass/polymer rods was formulated by mixing the ingredients in theproportions listed below:

33.3% weight of a superabsorbent polyacrylate precursor solution(aqueous), available commercially as Stockhausen 63815 from StockhausenInc.;

25.0% weight of a urethane film-forming polymer, Witcobond W290H,available from Witco Chemical Co.; and

41.7% weight of a 1% aqueous acrylamide solution, Drewfloc 270, which isavailable commercially from Ashland Chemical Inc. Example 2

In this coating composition for pultruded rods, the ingredients werecombined as follows:

28.6% weight Stockhausen 63815 superabsorbent polyacrylate precursorsolution;

35.7% weight urethane film-forming polymer, Witcobond W320, availablefrom Witco Chemical Co.; and

35.7% weight of a 1% aqueous solution of Drewfloc 270.

Example 3 Water Resistance Testing

An exemplary coating composition was developed according to thefollowing formulation:

40.0% weight Stockhausen 63815 superabsorbent polyacrylate precursorsolution;

7.5% weight Witcobond W320polyurethane film-forming polymer;

2.0% weight Emerlube 7440, a sulfonated mineral oil available fromHenkel Corp.;

2.0% weight of a 1% aqueous solution of Drewfloc 270; and

48.5% weight of deionized water.

The composition was applied to glass fiber reinforcement strandsdesigned for use in optical. cables. The reinforcements were thenimmersed in either deionized water or in a 1% saline solution. The swellrate in both the fresh water and the marine environments were determinedby measuring the percentage swell or increase in weight over timeintervals ranging from 0-20 minutes. As a comparison, strands coatedwith a dry waterblocking coating using granulated polymer powder werealso immersed in both the fresh and salt-water environments for the sameperiod of time.

The strands coated according to this invention and immersed in deionizedor fresh water showed a swell rate that was up to seven times fasterthan the swell rate for the rods coated with the dry, granulatedpolymer, within the first minute of exposure. The swell capacity or theoverall amount of swell was up to 270% higher in comparison to the drycoating. In the salt-water environment, the coating of this inventiondemonstrated a swell rate that was more than 6 times faster than the drygranulated coating within the first minute of exposure. The coating alsoshowed up to 50% more swell capacity than the dry coating.

These results clearly show that the coating solutions of the presentinvention achieve superior water absorption, and correspondingly,superior water resistance, when they are applied to articles that areexposed over prolonged periods to an aqueous fresh- or salt-waterenvironment.

Examples 4-5

The coatings of the present invention were further investigated todetermine their efficacy when applied to reinforcing fiber materialssuch as strands or rovings. Strands of glass reinforcing fibers werecoated with the invention and the percentage swell over time, calculatedbased on the total weight of coating and fiber was measured. Incomparison, strands coated with the dry, granular coatings were alsotested to determine the swell rate of the coating. In Example 4, thereinforcements were immersed in deionized water. For Example 5, thereinforcements were exposed to a 1% sodium chloride solution. Theresults obtained are included in Table 1 and 2 below: TABLE 1 Example4 - Water Absorption in Deionized Water Swell Rate^(a) (% swell/time)Time (minutes) Example 4 Comparison Sample 0 0 0 0.033 612 86 0.0833 677119 0.1666 730 168 0.25 nr¹ 210 0.333333 745 nr 0.5 751 264 0.666666 754nr 0.83333 758 nr 1 762 336 1.5 770 nr 2 778 nr 5 810 480 10 865 575 20975 650¹nr = not recorded^(a)Swell rate was measured as the percentage change in weight of thecoated strand per unit time.

TABLE 2 Example 5 - Water Absorption in 1% Sodium Chloride SolutionSwell Rate^(a) (% swell/time) Time (minutes) Example 5 Comparison Sample0 0 0 0.030 225 38 0.0833 237 47 0.25 265 81 0.5 276 88 1 295 99 2 312118 5 325 140 10 350 142 20 415 158It is believed that Applicants' invention includes many otherembodiments which are not herein specifically described, accordinglythis disclosure should not be read as being limited to the foregoingexamples or preferred embodiments.

1-27. (canceled)
 28. A superabsorbent coating for reinforcing fiberstrands or rovings, the coating comprising: a single layer of asubstantially homogeneous and non-particulate mixture of asuperabsorbent, water-swellable polymer, a non-particulateviscosity-modifying agent and a binder, said superabsorbent,water-swellable polymer demonstrating water absorption when said coatingis wetted and demonstrating water desorption when said coating is driedwithout loss of said superabsorbent, water-swellable polymer from saidcoating; said single layer coating exhibiting, when immersed in anaqueous environment, a swell capacity of up to about 400 times aninitial dry weight of said superabsorbent, water-swellable polymer, andsaid single layer coating further exhibiting, when applied to areinforcing fiber strand or roving, a swell rate of from about 300percent weight to about 2000 percent weight of a total weight of saidsuperabsorbent, water-swellable polymer and said reinforcing fiberstrand or roving within a first minute of being immersed in an aqueousenvironment.
 29. The superabsorbent coating of claim 28, wherein saidsuperabsorbent, water-swellable polymer includes a superabsorbentpolacrylate polymer.
 30. The superabsorbent coating of claim 28, whereinsaid single layer coating has a swell rate of from about 50 grams ofdeionized water per gram of said single layer coating when dry to about340 grams of deionized water per gram of said single layer coating whendry within said first minute of being wetted.
 31. The superabsorbentcoating of claim 28, wherein said single layer coating has a swell rateof from about 33 grams of salt water per gram of said coating when dryto about 66 grams of salt water per gram of said coating when dry withina first minute of being wetted.
 32. The superabsorbent coating of claim28, wherein said single layer coating has a swell rate of about 126grams of deionized water per gram of said coating when dry and about 50grams of salt water per gram of said single layer coating when drywithin a first minute of being wetted.
 33. The superabsorbent coating ofclaim 28, wherein said non-particulate viscosity-modifying agent isselected from the group consisting of alkyl celluloses, acrylamidepolymers and mixtures thereof.
 34. The superabsorbent coating of claim28, wherein said binder includes a film-forming binder selected from thegroup consisting of polyesters, polyurethanes, epoxies, latexes, andmixtures thereof.
 35. The superabsorbent coating of claim 28, whereinsaid single layer coating further includes at least one of a lubricantand a wetting agent.
 36. The superabsorbent coating of claim 28, whereinsaid reinforcing fiber strand or roving includes fibers selected fromthe group consisting of glass fibers, polymer fibers, carbon fibers,natural fibers, and blends thereof.
 37. The superabsorbent coating ofclaim 36, wherein said polymer fibers include fibers selected from thegroup consisting of aramid fibers, nylon fibers, Kevlar fibers,polyester fibers, polyethylene fibers, polypropylenes fibers, and blendsthereof.
 38. A superabsorbent coating for a composite article includingat least one reinforcing fiber material, the coating comprising: asingle layer of a substantially homogeneous and non-particulate mixtureof a superabsorbent, water-swellable polymer, a non-particulateviscosity-modifying agent and a binder, said superabsorbent,water-swellable polymer demonstrating water absorption when said coatingis wetted and demonstrating water desorption when said coating is driedwithout loss of said superabsorbent, water-swellable polymer from saidcoating; said single layer coating exhibiting, when immersed in anaqueous environment, a swell capacity of up to about 400 times aninitial dry weight of said superabsorbent, water-swellable polymer: andsaid single layer coating further exhibiting, when applied to saidcomposite article, a swell rate of from about 300 percent weight toabout 2000 percent weight of a total weight of said superabsorbent,water-swellable polymer and said reinforcing fiber material within afirst minute of being immersed in an aqueous environment.
 39. Thesuperabsorbent coating of claim 38, wherein said composite articleincludes a rod, cable or article formed from a pultrusion operation.